Field
The following description relates generally to wireless communications, and more particularly to communication of scheduling requests.
Background
Wireless communication systems are widely deployed to provide various types of communication content such as, for example, voice, data, and so on. Typical wireless communication systems may be multiple-access systems capable of supporting communication with multiple users by sharing available system resources (e.g., bandwidth, transmit power, . . . ). Examples of such multiple-access systems may include code division multiple access (CDMA) systems, time division multiple access (TDMA) systems, frequency division multiple access (FDMA) systems, orthogonal frequency division multiple access (OFDMA) systems, and the like. Additionally, the systems can conform to specifications such as third generation partnership project (3GPP), 3GPP long term evolution (LTE), ultra mobile broadband (UMB), evolution data optimized (EV-DO), etc.
Generally, wireless multiple-access communication systems may simultaneously support communication for multiple mobile devices. Each mobile device may communicate with one or more base stations via transmissions on forward and reverse links. The forward link (or downlink) refers to the communication link from base stations to mobile devices, and the reverse link (or uplink) refers to the communication link from mobile devices to base stations. Further, communications between mobile devices and base stations may be established via single-input single-output (SISO) systems, multiple-input single-output (MISO) systems, multiple-input multiple-output (MIMO) systems, and so forth. In addition, mobile devices can communicate with other mobile devices (and/or base stations with other base stations) in peer-to-peer wireless network configurations.
Moreover, for example, a base station can configure dedicated scheduling request (SR) resources to one or more devices to facilitate communicating SRs for uplink resources. In this regard, when a device needs to transmit user plane data, the device can wait for SR resources, transmit an SR over the SR resources, and receive an uplink grant from the base station, over which the devices can begin transmitting the user plane data. Latency associated with obtaining the uplink grant can be reduced at least in part by configuring the dedicated SR resources at frequent time intervals (e.g., to reduce the wait time for such resources at the device); however, this can also introduce overhead to an associated control channel over which the dedicated SR resources are configured for the device.
In one proposed solution to this issue, a device can receive contention-based radio network temporary identifiers (CB-RNTI) from a base station at frequent time intervals (e.g., 1 or 2 ms in LTE) related to uplink grants and can monitor control resources for contention-based uplink grants on a shared resource channel (e.g., physical uplink shared channel (PUSCH) in LTE). When the device needs to transmit user plane data, it can receive a contention-based grant in the given time interval and transmit the data thereover. In this solution, devices can collide over the uplink resource grant. In an example, where the number of devices at a base station increases, however, the time required to recover from the collisions over the shared resource channel may outweigh the time savings of allowing the devices to obtain the contention-based grant without waiting for SR resources for requesting the grants.